1. Field of the Invention
The present invention relates to a monitoring apparatus for moldings molded by an injection molding machine, and particularly relates to a molding monitoring apparatus that allows a tendency for generation of molding defects to be grasped by acquiring images of a plurality of moldings.
2. Description of the Related Art
When a defect is generated in a molding molded by an injection molding machine, specifying a generation position of the defect is extremely important in taking a measure against the defect. For example, when a burr or a short shot is generated at an end of the molding, there is a possibility that a pressure in packing process is inappropriate. When silver is generated around a gate of the molding, there is a possibility that an injection speed is inappropriate. In addition, when carbide is randomly viewed on a surface of the molding, there is a possibility that a resin temperature is inappropriate.
Recently, various means have been proposed to acquire an image of a molding, and detect the above-described defect such as the burr, the short shot, the silver, the carbide, etc. based on the image. For example, JP 2009-061786 A discloses a die monitoring apparatus that acquires an image of a molding, and operates a molding machine or an attachment device according to a position at which abnormality occurs. Japanese Patent Application Laid-Open No. 3-231824 discloses an injection molding machine monitoring apparatus that acquires an image of a molding using a video camera, and determines the presence/absence of abnormality using brightness of a mesh-patterned detection unit region. Japanese Patent Application Laid-Open No. 2007-160642 discloses a molding machine management system that compares an image of a non-defective product with an image of a defective product, and stores difference data thereof. Japanese Patent Application Laid-Open No. 2006-297759 discloses a nonconforming item generation prevention molding system that specifies a type or a degree of a defect based on a captured image of a molding, and corrects a molding condition.
In the above-described conventional arts, identifying a tendency for generation of defects based on defect generation statuses in a plurality of moldings is effective to determine whether the above-described defect such as the burr, the short shot, the silver, the carbide, etc. is accidental or results from the above-described molding condition such as the pressure, the injection speed, the resin temperature, etc.
However, all the above-described technologies disclosed in those patent documents described above determine quality of each molding rather than grasping a tendency for generation of defects.
Meanwhile, Japanese Patent Application Laid-Open No. 2014-69382 discloses a defect-cause determination system capable of totalizing the number of instances of defect generation for each defect generation place to indicate the number in a graph, and comparing process values of an injection molding machine among a plurality of shots including a shot at which a defect is generated. However, this conventional art cannot compare defect generation places among a plurality of shots having different molding conditions, and thus has difficulty in specifying a molding condition corresponding to a cause of a molding defect.
As described above, even though all the above-described conventional arts contribute to a measure against an accidental molding defect, these conventional arts have difficulty in establishing an optimal molding condition and embodying long-term stable molding.